294 Transactions.— Zoology. 
of the posterior end of the stomach, and the whole alimentary canal appears 
like an almost simple narrow tube greatly exceeded in calibre by the oviducts. 
The intestine has a well-marked duodenal section or bursa Entiana (b.e) 
into the left lateral wall of which the stomach opens by a small pylorus 
(py) guarded by a well-marked annular pyloric valve. The rest of the in- 
testine is somewhat narrower than the stomach, and of tolerably uniform 
diameter except at its posterior end, where it narrows considerably before 
entering the cloaca ; with the dorsal wall of this posterior portion or rectum 
(r) is connected the large rectal gland (r. gl). 
The stomach is supported by a mesogaster attached along the anterior 
two-thirds of its dorsal side: the intestine is free save for a mesorectum 
attached to the rectal gland, and to the dorsal wall of the rectum posterior 
to that structure. 
The spiral valve (sp.v) is the most perfect apparatus of the kind I 
have yet examined. It belongs to what I have elsewhere* described as 
** type C," that is, the width of the valve is greater than the semi-diameter 
of the gut, and the plane of any part of it is inclined, from its attachment 
to the intestinal wall, forwards or towards the duodenal end. There are 
twenty-seven turns to the valve, the total length of the intestine being 
inches. The muscular wall of the intestine (w) is greatly thickened, the 
thickening being often especially well marked between the turns of the 
spiral valve. Thus the absorbent surface of the mucous membrane is 
further inereased, an additional obstacle is offered to the passage of the 
intestinal contents, and great museular power is obtained for their propul- 
sion towards the cloaca. This great development of the intestinal muscu- 
lature is an exaggeration of what I described, in the paper just referred to, 
—in Seyllium canicula. | 
The liver (fig. 1, lr) is of immense size, its two lobes reaching quite to 
the posterior end of the abdominal cavity; it weighed 9 lbs. in the fresh 
state. There is no gall-bladder ; the wide bile-duct (figs. 2 and 8, b.d) 
passes from the liver in the gastro-hepatic omentum (fig. 1, g. h.o) to the 
right side of the stomach, and then proceeds directly backwards to open 
into the anterior wall of the bursa Entiana (fig, 2). 
The pancreas (figs. 1 and 2, pn) consists of two lobes: one (fig. 2, pn) 
closely applied to the ventral surface of the intestine, just beyond the bursa 
Entiana; the other (pn^) passing backwards and outwards to the left side of : 
the spleen (spl), and surrounding the right mesenteric vein (r.m.v). The 
spleen (spl) is large, compact, scarcely at all lobulated, and very distensible, 
swelling to two or three times its orginal size when injected through the 
arteries. 
* On the Intestinal Spiral Valve in the genus Raia,” Trans, Zool. Soc., vol. xi., pt. 2, 
1880, p. 49. : 
4 
P 
E, 
1 
E 
E. 
3 
A 
E 
Ji 
5 
a 
